In order to prepare for each cases to make high functional active prostheses, respective design considering of patient's movements, behaviors, and working forms should be performed. For this purpose, a concept of the simulation surgery is recently being established. This study was aimed to design dynamically the active proshtetic arm using the dynamic design system method, which is now spreading in other world, as the simulation surgery. In addition to this, the cheaper work station computer was aimed to use this method.For these purposes, in the first year (1994) , the dynamic design system was mainly established. That is, planning of the whole system, preparing the computer hardware and software for the three-dimensional realtime simulation, and designing of the whole system were performed.In the last year (1995) , our study was planned that the software for the three-dimensional realtime dynamic simulation, which takes main role of the system, was developed by Hasegawa, and that planning of the whole system and evaluating the simulation was performed by Miyake, addition to these, medical evaluation and summarizing this study was also performed by Miyake. Consequently, 1) preparing and performing the simulation was done by the graphic work station computer, which was purchased in 1994.2) Evaluation of the simulation and a object design was performed. 3) Medical evaluation was performed.Contrary to these results, because of plenty many of living muscle movements, analytical results, a little discussions need more to accomplish a clinical useful system.